An archive apparatus that uses high-capacity optical discs (hereinafter referred to as “discs”) has been in practical use. Examples of a storage apparatus in a data center include a storage apparatus that uses magnetic tapes as media. The discs are suitable for a cold archive aimed at long-term storage as compared with the magnetic tapes. For example, the following PTL 1 describes an archive apparatus capable of storing 12 discs in a magazine and handling the discs in units of magazines.
As described in PTL 1, storing 12 discs in one magazine has advantages in that the number of discs that can be accessed at a time increases and it is possible to record or reproduce a large amount of data at a time as compared with the case where discs are mounted in drives one by one. However, it is desired that a larger amount of data is recorded or reproduced in the data center.
The applicant of the present application has previously proposed a disc medium storage apparatus (hereinafter referred to as a disc tray as appropriate) in which a larger number of discs are stored in a case. This disc tray is capable of storing 64 (=4 rows×16) discs in the case with an upper surface thereof opened. The case has a box shape and is made of a synthetic resin. A large number of such disc trays are stored in a storage rack. A tray conveying robot takes out a predetermined disc tray from the storage rack and conveys the disc tray to disc drives so that the disc drives simultaneously record or reproduce data on/from the plurality of discs.
Normally, a disc tray once stored in the storage rack of the disc archive apparatus is not taken out from the rack. This is because there is a possibility that dust or the like enters into the storage rack from the outside. However, there may be a disc whose capacity has become full, a disc that has become defective, or a disc tray that has hardly been accessed and only needs to be stored off-line, for example. In consideration of this point, a dedicated storage rack is provided to take out a disc tray or mount a disc tray in a space of the storage rack from which a disc tray has been taken out. It is noted that although one possible consideration is to take out an unnecessary disc tray from a maintenance hatch provided in the storage rack, there is a risk that the internal discs jump out and scatter when the disc tray is tilted while being taken out.